Singapore state investor Temasek Holdings has expressed interest in buying into Chinese conglomerate HNA’s Hong Kong-based carriers, Hong Kong Airlines and Hong Kong Express Airways, according to a source familiar with the matter. However, an investment in the unlisted Hong Kong carriers by Temasek remains subject to a due diligence process that has yet to begin, said the source on condition of anonymity. The Singaporean investor would likely emerge as only a minority holder in the Hong Kong airlines, which control valuable slots at Hong Kong’s capacity-constrained airport, if a deal is completed, the source said. Temasek and the debt-laden HNA, an aviation-to-financial services conglomerate, last week signed a memorandum of understanding to explore business partnerships in aviation and logistics. A second source familiar with the matter said HNA is looking to raise funds ...